Russia on Monday ignored
Western calls to release three Ukrainian naval ships it fired on
and captured near Crimea at the weekend and accused Kiev of
plotting with its Western allies to provoke a conflict.

Kiev in turn accused Russia of military aggression and put
its armed forces on full combat alert, saying it reserved the
right to defend itself. Ukrainian lawmakers were due to decide
whether to introduce martial law for two months later on Monday,
a move President Petro Poroshenko has backed.

With relations still raw after Russia's 2014 annexation of
Crimea from Ukraine and its backing for a pro-Moscow insurgency
in eastern Ukraine, the crisis risks pushing the two countries
towards a wider conflict and there were early signs it was
renewing Western calls for more sanctions on Moscow.

The crisis erupted when Russia's border patrol boats
belonging to Russia's FSB security service seized two small
Ukrainian armoured artillery vessels and a tug boat after
opening fire on them and wounding several sailors on Sunday.

They had been trying to enter the Sea of Azov from the Black
Sea. The FSB said it had opened a criminal case into what it
called the ships' illegal entry into Russian territorial waters.

On Monday maritime traffic resumed in the Kerch Strait,
which separates Crimea from the Russian mainland, but Moscow
showed no sign of releasing the ships and their crews.

COMBUSTIBLE

The stand-off is more combustible now than at any time in
the past four years because Ukraine has rebuilt its armed
forces, previously in disarray, and has a new generation of
commanders who are confident and have a point to prove.

Kiev is also strengthened by the knowledge that most Western
governments, especially Washington, lean towards Ukraine and are
liable to view Russia’s version of events with some scepticism.

NATO called an emergency meeting with Ukraine on Monday
after the alliance's head Jens Stoltenberg held a phone call
with Poroshenko. He offered NATO's "full support for Ukraine's
territorial integrity and sovereignty."

European Council President Donald Tusk also condemned
Russia's seizure of the vessels and urged it to return the
vessels and crews.

Domestic politics adds to the combustibility of the
situation. Poroshenko faces a tough re-election fight early next
year, with opinion polls showing him trailing his opponents.

Russia's President Vladimir Putin has also seen his high
approval rating fall because of unpopular domestic policies. In
the past, successful military action beyond Russia’s borders has
buoyed his popularity.

Using bellicose language, the Russian foreign ministry
accused Kiev of deliberately staging what it called a
provocation to harm Russian interests and said it would react
harshly to any attempts to undermine its sovereignty,

"It's obvious that this painstakingly thought-through and
planned provocation was aimed at igniting another source of
tension in the region in order to create a pretext to ramp up
sanctions against Russia," the ministry said in a statement.

Markets are highly sensitive to anything that could trigger
new Western sanctions, and therefore weaken the Russian economy.
A fall in the price of oil -- Russia's biggest source of revenue
-- has made its economy more vulnerable.